1. Field of the Invention
The present invention relates to a nozzle for boring through earth which may be steered in a desired direction.
2. Discussion of Related Art
Prior art devices which employ one or more high-pressure liquid cutting jets on a rotary cutting borehead at the end of an umbilical. At least one jet is offset from center of the borehead. The borehead is designed to be inserted into the ground and rotate while the jets are operating. The jets are timed to fire with higher pressure at a specific side of the borehead of each rotation. If timed properly, the jets would cut deeper on one side of the borehead as opposed to other sides thereby steering the borehead and umbilical toward that side.
Since borehead rotation is required, the rotating tip creates significant torques on the umbilical and other associated equipment. Due to the engineering requirements, it is doubtful if a device can be constructed using this technology for rapid boring to depths on the order of several hundred meters.
There is also the problem of pressure loss due to friction. Water or another incompressible fluid is pumped to the borehead through the umbilical. As the fluid passes through the umbilical, there are considerable frictional forces which reduce the pressure delivered at the borehead. Therefore, the pressure applied at the pump end of the umbilical must be much greater to produce adequate force at the borehead. Therefore, this technology is limited in the depth in which it can bore.
Currently, there is a need for a steerable device for quickly boring a hole to a desired destination several hundred meters away.